Anion Gap Calculation

The Anion Gap (AG) is a value derived from the charges of serum electrolytes, mainly sodium (Na⁺), potassium (K⁺), chloride (Cl^-), and bicarbonate (HCO₃^-). The calculation is indicative of the concentration of other anions not measured directly by routine blood testing. AG is commonly used in clinical practice to help identify causes of metabolic acidosis. A higher AG indicates the presence of anions like lactate, ketoacids, or ingestants (e.g. salicylates). A normal range for AG is typically 3 to 11 mEq/L when potassium is considered, but reference values can vary by laboratory.